Hello, the question I am asking has been asked by many on this forum, but not in the right perspective, I think.
But here goes. Why is a critically damped Q factor bad? Psychoacoustically.
In my opinion, if critical damping is between overdamped and underdamped, then this is the ideal Q factor for most applications.
But it seems that psychoacoustically some people don't like it, saying that it sounds weak, thin and that there is not much advantage in tuning a speaker with this Q factor.
Others say that it has better transients and that the speaker has better time domain with this Q factor.
There are also those who agree that a change in Q factor, for example: from 0.707 to 0.500, will not be audible, because the acoustics of the room dominate most of the low frequency sound [120hz or less].
Really, this question is about how a critically damped Q factor [0.5] can affect the sound of a speaker both in measurements, such as impulse response and step response, and psychoacoustically for people.
[Other]
For this question, the speakers can be of any type, for example: mid-rangers, subwoofers, full-rangers, etc.
But here goes. Why is a critically damped Q factor bad? Psychoacoustically.
In my opinion, if critical damping is between overdamped and underdamped, then this is the ideal Q factor for most applications.
But it seems that psychoacoustically some people don't like it, saying that it sounds weak, thin and that there is not much advantage in tuning a speaker with this Q factor.
Others say that it has better transients and that the speaker has better time domain with this Q factor.
There are also those who agree that a change in Q factor, for example: from 0.707 to 0.500, will not be audible, because the acoustics of the room dominate most of the low frequency sound [120hz or less].
Really, this question is about how a critically damped Q factor [0.5] can affect the sound of a speaker both in measurements, such as impulse response and step response, and psychoacoustically for people.
[Other]
For this question, the speakers can be of any type, for example: mid-rangers, subwoofers, full-rangers, etc.
Tune a bass reflex driver/cabinet two-way stand mount combination so that the Q of the system is rather higher than optimal for 'perfect' damping and the output rises between 80 Hz and 120 Hz which gives the listener the impression of bass extension that actually isn't there.
This method of tuning emphasises the second harmonic of 40 Hz and the listener assumes that the 80 Hz output is indicative of 'deep' bass.
As far as I experienced from my listening tests you have no advantage of a too low Q like 0.5 because it simply is not loud enough and psychoacoustically the mid frequencies dominate the sound.
By electronically correcting the amplitude you gain nothing as the Q is then the summed electric and mechanic Q forming the higher Q. You end up turning the bass up in order to adjust it to your taste.
I worked some years intensively with a dsp assisted high Q fullrange driver system. And you could adjust it to the Q you desire.
Psychoacoustically I had days I turned the 40hz up by one or two db - the other days back again.
Same with the 150hz region.
Electrically there is only one right linear alignment which is correct. But the perception can change and you play (in small grades) with the highs and lows with the dsp.
No pardon was given in the mids here I never touched the once found perfect balance of on and off axis summed linearity.
Maybe you can put half a db more or less here over two octaves in order the emphasize the mids or not.
With dsp you could tune the bass perception between dry and articulate and slow and mellow without changing the box.
By electronically correcting the amplitude you gain nothing as the Q is then the summed electric and mechanic Q forming the higher Q. You end up turning the bass up in order to adjust it to your taste.
I worked some years intensively with a dsp assisted high Q fullrange driver system. And you could adjust it to the Q you desire.
Psychoacoustically I had days I turned the 40hz up by one or two db - the other days back again.
Same with the 150hz region.
Electrically there is only one right linear alignment which is correct. But the perception can change and you play (in small grades) with the highs and lows with the dsp.
No pardon was given in the mids here I never touched the once found perfect balance of on and off axis summed linearity.
Maybe you can put half a db more or less here over two octaves in order the emphasize the mids or not.
With dsp you could tune the bass perception between dry and articulate and slow and mellow without changing the box.
I had more than once bad experience with low Q fullrange drivers with no crossover on a high damping transistor with low R thick cables.
Happened you cannot correct the bass with dsp. Too much damping.
Here you need thin cables or inserted R from crossover network or a current driven amplifier or a tube amp.
So there can be excess in low Q which electronically could not be corrected. It sounded even linearized overdamped "the speaker could not walk".
Its a rare situation as 99% of loudspeakers are not of this type.
Happened you cannot correct the bass with dsp. Too much damping.
Here you need thin cables or inserted R from crossover network or a current driven amplifier or a tube amp.
So there can be excess in low Q which electronically could not be corrected. It sounded even linearized overdamped "the speaker could not walk".
Its a rare situation as 99% of loudspeakers are not of this type.
I've heard of a theory that if the Q factor is very low, all the signals can be absorbed, that is, the useless signal (ringing, overshot) and the useful signal. Interesting to know that this can happen in practice.
I’ve made several low Q subwoofers and to my ear they sound the best, drums are great! The downside is there isn’t much reverb or room sound that comes through or is added as ringing or bloom in the bass, so they can sound dry. For orchestral music I think it’s great, it’s a natural sound of the recorded room sound. For electro dance music where there is an amorphous throbbing bass it may be too dry. I think a low Q subwoofer blends well with resonant concrete basement listening rooms. The only problem is the enclosures tend to be large, sometimes too huge of an enclosure is required to get low bass response. Also, the roll-off tends to match the room gain to make a more realistic bass response.
Hi, yeah, OP be careful to understand what is the context for any written description of sound. One could say 0.5Q is best while another something else, just because their rooms have different effect on the sound. Rooms have huge effect on bass in general. This makes any comments regarding bass highly dependent on context. All sound related commentary, that do not come with the actual perception, are highly context relevant. This means that only part of comments you read have relevance to your context. Arthur Jackson gave some ideas about context where his observations are relevant.
Do you know what is your context, and which comments are relevant to it and which are not?🙂 Context is the whole playback and system and listener, with bass mainly the room and any processing, positioning and preferences. Simplest possible example: A disco dude might not mind about proper kick, while a jazz enthusiast might think it's overwhelming.
Do you know what is your context, and which comments are relevant to it and which are not?🙂 Context is the whole playback and system and listener, with bass mainly the room and any processing, positioning and preferences. Simplest possible example: A disco dude might not mind about proper kick, while a jazz enthusiast might think it's overwhelming.
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Critically damped isnt bad.
On average people dont like making large boxes.
Or make wild guesses because they think it doesnt " look" right in sim.
Depends on the driver.
On average people dont like making large boxes.
Or make wild guesses because they think it doesnt " look" right in sim.
Depends on the driver.
Q as its being discussed in this thread is not a voicing... its the shape of the a filter knee. I don't think it has any regard to the slope either.... Meaning you could have the same Q with different slopes past the knee... The point that stands out to me, is where. Where the Filter knee exist in the spectrum is also a separate from Q. So if your system is flat to 20hz for example, and then rolls off, 12db/oct or 48db/oct it can have a Q of 0.5 at the knee....
Slope affects Ringing as well, so a Q of 0.5 isn't the final say.... I think a 2nd order filter with a 0.5Q is the only true critically damped option. The Under Damp, or Over Damp factor is centered around the Filter knee as well... So if Your roll off doesn't happen till 20hz.... there is no ringing issues well above 20hz, regardless of the Q and Slope, with respect of the how far away from the center of the Filter, attenuation or subtraction of signal level, is happening.
The crossover sections of the spectrum have to analyzed separately, is what I understand. So if you have a ringing HP filter at 80hz, mated to a LP filter at 80hz (or not) and the resulting FR is neutral through the crossband, the ringing of the HP is still there, to the best of my knowledge.
So why is Critically damped, bad? It isn't.... its just a factor towards accuracy. If you like it or not, might have to do with how you've used it or purely subjective taste. The shape of the in room response is the final say, as well, as far as I know. Meaning its not as simple is just setting a 0.5Q to a 2nd order HP/LP.... This shape needs to be the in room, at listening position, response.
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The ideal response is that the driver cone closely follows the input signal which occurs when there are no substantial resonance/s present. Resonance/s are introduced in order to raise the output level at the low frequency end of the passband at the price of the cone no longer closely following the input signal. There is no ideal way to degrade the response. What matters is how much degradation is acceptable in exchange for an increase in low frequency output. This trade-off varies significantly with speaker configuration (size and number of way), the strength of room resonances (desk speaker, room mains, sub), etc... Without this context answers will only be applicable in limited circumstance (if that!). I would suggest viewing claims Q=XXX is the universal answer with a fair degree of skepticism.
PS The "best" approach is likely to be a big strong motor with active control of the driver cone to raise the output while maintaing that the cone closely follows the input signal.
If a speaker has an fb of 50 Hz and a Qb of 0.5 it would definitely sound aenemic. But with an fb of 25 Hz and a Qb of 0.5 things start to look (better: sound) different. I once tried this by EQing a closed box to this by the use of an biquad filter and the result was great !
Regards
Charles
Regards
Charles
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System I heard was called Servo Sound in the early seventies. These were small speakers at the time but sounded terrific then. To remember this from 55 years ago, it must have made some impression on me.
From what was explained then, these had an extra voice coil winding that sat in the amplifier feed back path.
I disagree with that (@Ron E ’s link). Woofers don’t just reproduce sound at a steady state. Step response actually does matter.
I remember them. I don’t know why the technology hasn’t become more popular. Seems like computer controlled subwoofers would be great.
I stand to be corrected but, I think it was a Danish company that made them. I am now curious about where they went.
Found this: is an active high fidelity loudspeaker system[1] which was developed by the Dutch Philips brand in the early 1970s
Found this: is an active high fidelity loudspeaker system[1] which was developed by the Dutch Philips brand in the early 1970s
I have a pair of Entec SW-5.
It's one of the few "woofers" that matches with a Magnepan.
It's also a rather ugly thing... specially when the foam cover disintegrates with time.